July 23, 2014

Does your hair get looser or curlier with length?

 

One of the many conundrums in the world of curly hair is that some people experience a relaxation of their curls as their hair gains length, while others experience the converse: their curl increases with the length of their hair.

The former trend makes sense without having to give it much thought. Longer hair has more weight and is pulled down by gravity, which lengthens and loosens the curl. However, the latter phenomenon seems counterintuitive.

This behavior can be so perplexing, causing curls to disappear with a haircut or to suddenly begin developing as someone grows their hair out for perhaps the first time. While this seeming contradiction may be baffling and even frustrating, it is possible to understand what is going on if one looks at what causes hair to curl and some mathematic principles that can be used to describe curly hair.

Read On!>>>


Morphology of Hair

Human hair is a marvelously complex biomaterial, comprised of many nanoscale substructures woven together into intricate patterns, both beautiful and functional. The building block of hair is the protein keratin, which is made up of long chains of amino acids. The amino acids in the keratin strands have very specific bond geometries that give the fiber an α-helical conformation. Individual keratin fibers bundle together with other keratin fibers to form aggregates called microfibrils. Clusters of microfibrils bundle together into macrofibrillar structures which occupy the central cortex of the hair. Fatty acids and keratin-based cuticles encapsulate the entire strand.

Human hair keratin is made up of 14 percent sulfur-containing amino acids (cysteine and cystine). It is from these amino acids that many of the properties of hair are developed, particularly curl. When two strands of keratin are adjacent to one another, the –SH bonds for nearby cystine groups can be oxidized to form a disulfide (S-S) bond between the two strands. This is a chemical crosslink that ties the adjacent keratin strands together. A high proportion of disulfide bonds twist the hair strand into a helical pattern. Adjacent hair strands tend to assume the same pattern, and then cluster together into multi-helical structures that form curls. In this manner, the nanoscopic structure is repeated at the macroscopic level. Nature loves patterns.

The permanent wave process exploits this by breaking disulfide bonds and then reforming them (and forming new ones) with hair locked into the desired helical shape.  

There are a number of factors that contribute to degree of curliness.  These include, but are not limited to:
  1. Shape of the hair follicle – Teardrop-shaped, cylindrical and oval follicles all produce hair with differing degrees of curl.
  2. Angle of emergence of hair from scalp – Super curly hair has been found to emerge from the scalp at a different angle than straight hair.
  3. Cross-sectional geometry of hair strand – Completely cylindrical hair strands are straight, while oval strands have more wavy characteristics. Flat, ribbon-like strands result in extremely kinky curly hair.
  4. Quantity of disulfide bonds – A higher concentration of disulfide bonds results in a more pronounced helical pattern.
  5. Prevalent morphology of cortex cells – The aggregation pattern of the macrofibrillar structures in the cortex affects the degree of curliness.
  6. Presence of other genes or proteins – Several different research groups are exploring the presence of a protein that seems responsible for curl formation.
Helical Structures

We have established that the helix structure repeats throughout the hair from its most basic molecular building blocks into the bulk hair pattern. But what exactly is a helix? You may recall the spiral staircase geometry of the DNA-double helix strand from high school biology. A helix is a ribbon-like coil that occupies three-dimensions and is governed by specific trigonometric equations used to describe the length of revolutions and the pitch angle.

X (t) = r cos t
Y(t) = r sin t
Z = ct

Where t = [0,2π], c = constant, r = radius, and 2πc = vertical separation of the loops.

This three-dimensional mathematics can become a bit tricky to visualize, so it can be easier to eliminate the third dimension (z) and think in terms of two-dimensional sine waves. Sine waves can be used to model many different types of oscillating cycles that occur throughout nature, such as sound waves, visible light waves, and radio waves. In trigonometry, we call the length of time or distance it takes to complete one full cycle the period.

If one were to examine a spiral hair curl, it would be possible to see that one full curl revolution would be equal to one complete cycle or sine wave. The distance required to complete one full cycle varies for everyone. Very kinky curly hair would complete more revolutions per the same distance than hair that is less curly. Think of it as higher frequency curl pattern.

Take an example of three different people, with three different degrees of curl, all having hair nine inches in length.

Person A: Her hair completes one full spiral in one inch. In nine inches, it complete nine full revolutions and appears to very kinky curly. If she were to grow it out longer, the weight would eventually stretch the curls out a bit, so that her curl pattern would relax. She would be said to have Type 4 hair.

Person B: Her hair completes one one full spiral every three inches. In nine inches, her hair completes three full revolutions and appears to be mildly curly. If she were to cut it short, it would appear wavy or even straight, but grown longer, it would develop into well-defined spiral curls. She would probably be said to have Botticelli or Type 3 hair.

Person C: Her hair completes one full revolution in six inches. In nine inches of length, her hair only completes one-and-a-half revolutions and appears merely wavy. If she were to trim her hair to be six inches or less in length, it would appear straight. If she were to allow it to grow out to be very long (eighteen inches or more), she would begin to see a pronounced curl pattern emerge. She might be said to have Type 2 or Type 3 hair, or even straight hair, depending upon its length.

Final Thoughts

Human hair is such an intricate structure, and it varies so much from person to person. The helical structure present in our very DNA makes itself apparent on a nano-level in the keratin strands that make up the foundation of our hair and is repeated at higher and higher levels until it is expressed in the gorgeous spiraling curls of our “kinky-haired” sisters and brothers.

Most of us with curly hair find ourselves with a mixture of all sorts of curl types on our heads, and we spend a lot of time and effort attempting to enhance, define and control them. Those with hair that takes longer lengths to really develop and show the curl patterns would do well to keep that in mind when cutting out hair. Lack of caution can lead to a disappearance of those precious curls. Remember the mathematics.

In order to get the best results in your curl pattern, you can figure out what your length for one revolution is and keep it in mind when growing or cutting your hair.


CN Says:
My springiest and tightest curls occur when my stretched hair reaches shoulder length (or above).  However, due to its fine nature, at this length, my hair is particularly light weight and doesn't give me much of any hangtime unless I use a ridiculously tacky and heavy gel or cream styler.  My optimal length for volume, weight and good, even curl definition is between armpit and boob length.  Any longer than that and my curls gets droopy, with some of the finer pieces pulling straight-ish, I lose volume and the shape goes all weird. I've also learned that unlike many fine curlies, for some reason, layers are my friend! 

19 Weigh in!:

CurvyCurly said...

Interesting article. I have fine hair and the longer is gets the stringier and thinner it appears. I also have several different textures throughout however the most difficult area to blend is the loose curls at the nape of my neck. Allowing my hair to grow past armpit length causes me to loose volume and hair to look thin and stringy in the back. Shorter bobs seem to look better on me. Good info.

CurlyNikki said...

I have looser curls up front which are more difficult to work with then the thicker and more defined hair in the back. It gets stringy quick :-/

Davina916 said...

Thanks for the info.

ChakaKhanian said...

As my hair gets longer, I've found that it goes through the same process as Curly Nikki's. It looks like it just hangs with no personality, but when I get it cut, you can't tell me nathan!

CurvyCurly said...

Ain't nothing like a good cut. Many ladies struggle with sacrificing length for health, volume, and style.

ChakaKhanian said...

Precisely!

Sweetdrk1 said...

I guess I will NEVER get hang time because uhm I don't know about letting it get much longer O-O

Dannielle said...

I love this article. Although she mentions topics from chemistry, trigonometry, and even multivariable calculus, the article is still understandable. It is very well written and informative. Thanks for posting it. Now I'm off to measure the length of one of my curl's revolutions. :)

Megan M. said...

Math not my best subject, now hair math wooow =0 lost all ready, My curls are loose in the front (the whole front) and the rest is tight and springy when I pineapple at the top of my head they stretch out and get stringy it makes my wash n go's look a mess, so I do the low pony .

RazzyYazzy said...

Love math and enjoyed reading this article. Most of my curls are stretching with length. Just the other day my husband said, "hey look, you have a perfect little spiral right there (referring to my hairline)" No need to do the math on curl revolutions when half an inch of hair forms a perfect cylindrical curl. But the rest of my head! Ha, wavy hair at the nape, and less defined coils, zig-zaggy waves at the crown. Jeez, how do you plan ideal lengths for mixed up curl patterns!

CurvyCurly said...

I totally forgot to mention that the woman in the photo is drop dead gorgeous and her hair is amazing. #thatisall.

CurvyCurly said...

Girl I feel you. I keep my hair (mixture of 4 and 3) in a bob shape and no longer than armpit length when stretched because of the numerous textures throughout my head. They really become pronounced the longer it gets, especially that loose stringly stuff (3bish) in the nape of my neck...what tha. The stuff at my crown is just a frizzy undefined bush for real. My wash-n-go's look much better when my hair is at medium 'fro length however I allow it to grow a bit longer in the harsh summer and winter when I do more stretched styles that I bun or pin up.

Imani BeautifullyPissed Monroe said...

Wow and i just thought my hair could never change lol

Bridget Daniels said...

OMG! You guys have solved a problem that I have been having with my hair for the last few months. My hair is multi-textured as well (mix of 4s and 3s with a frizzy patch at the crown). I have been growing my hair out and my once super easy wash-n-gos have turned into hot mess wash-n-nos. This has been a serious problem for me since this is my go to hair style. I have tried almost every product out there in an effort to "fix" the problem to no avail. I just end up pulling it back into a bun or low pony after each failed attempt. After reading the article and the comments, a light bulb went off and I was reminded that I began my curly-haired journey with a super cute bob cut. It must be time for a hair cut. (Duh!) Currently protective styling (mainly out of frustration), but I plan to get a haircut soon. Thanks so much!

ss said...

I have tight 4c coils BUT the hair that frames my face is LOOSER - not 4a or 3c looser - but stringy stretched-out 4c tendrils at the front and side edges of my tapered WNG. Go figure o_0
It looked funny when I set them with a perm rod or bobby pin, so I started cutting it off - but quickly came to my senses,
The pattern was like this before I used henna, and it's only happening on my edges. LOL!

CurvyCurly said...

Bridget trust me, it took me a while for the light bulb to go off as well. ;-) Although we hate to say it or admit it sometimes shorter hair looks and performs much better but you know how we love our length right.....

Shashou said...

Wow that is a lot to take in. But great info. My hair is pretty much spring all over Type 4a and b. In the middle it gets bushy and the sides right by my ears are a very different curl pattern. Probably type 3c. I had really seen any change in my curl pattern even when I cut. So I have no idea how to identify what my hair would do.

Derika said...

You and me both hun! I was so confused reading the article! Lol

Derika said...

I have very tight curls like 4b around my edges and the nape area. Then I have a few 4a curls in the crown of my hair.

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